Thirteen cyathane diterpenoids with acetylcholinesterase inhibitory effects from the fungus Cyathus africanus

Secondary Metabolites of Bird’s Nest Fungi: Chemical Structures and Biological Activities

“…38 Notably, the newly reported cyathin Q (82), cyathin T (85), and cyathin W (87) have a naming duplication with the known cyathin Q (41), cyathin T (39), and cyathin W (37) but correspond to different structures. 38 The group of xylosylated cyathane diterpenes possesses highly complex structures; striatins A−C (89−91) were first cyathane-xylosides to be isolated from bird's nests fungi. 39 Subsequently, these compounds were found to hydrolyze and generate three new cyathane-xylosides, striatals A−C (92−94), containing ketone and aldehyde groups.…”

“…In experiments testing the acetylcholinesterase inhibition of 36 , 43 , 51 , and 82 , their inhibitory rates were over 50% at a concentration of 40.0 μM, and the IC 50 values varied between 4.60 ± 0.85 and 8.70 ± 2.42 μM. Among them, 36 showed the strongest inhibitory activity with an IC 50 value of 4.60 ± 0.85 μM …”

“…The total synthesis of the key bicyclic [5/6] intermediate of 12 was established, and the reaction conditions were optimized . Cyathins Q–U (82 – 86 ), cyathins W–X ( 87 – 88 ), as well as four reported congeners, 36 , 43 , 51 , and cyathin I ( 52 ) were isolated from the liquid fermentation broth of C. africanus . Notably, the newly reported cyathin Q ( 82 ), cyathin T ( 85 ), and cyathin W ( 87 ) have a naming duplication with the known cyathin Q ( 41 ), cyathin T ( 39 ), and cyathin W ( 37 ) but correspond to different structures …”

“…Neocyathins K–L ( 113 – 114 ) were first two cyathane diterpenes with a 4,9- seco skeleton found in the cooked rice solid medium of C. africanus . Stercorin A ( 115 ) and cyathin V ( 116 ), another two other cyathane diterpenes with a 4,9- seco skeleton, were isolated from the liquid fermentation broth of C. stercoreus and C. africanus . The comparison of the NMR data showed that 116 and 113 share identical planar structures, except for the opposite configuration of the hydroxymethyl group at C-12 (Figure ).…”

“…24 Interestingly, compounds 27 and 36 are a pair of epimers first isolated from S. tenacellus. 22 Three new cyathane diterpenes, cyathin W (37), cyathin V (38), and cyathin T (39), were isolated from the solid medium of C. africanus, 25 and cyathin R (40) 26 and cyathin Q (41) 27 were derived from the same fungal.…”